Apparatuses for conveying particles, such as pulp fibers are known in the art. For example, there are numerous air-laying forming heads that utilize pinwheels and/or screens and/or sieves through which all of the particles traveling through the apparatuses pass. These known apparatuses do not separate a portion of the particles from the other particles as the particles are traveling through the apparatuses. As can be seen in FIGS. 1-4, the prior art apparatuses comprise multiple pinwheels and one or more screens or sieves, a single pinwheel and a screen or sieve, multiple pinwheels without screens or sieves. None of these prior art apparatuses separate particles traveling through the apparatus into two or more distinct groups. In other words, none of the prior art apparatuses divert and/or remove only a portion of the particles from the stream of particles traveling through apparatus, especially using inertial and/or aerodynamic characteristic differences in the particles to cause the separation.
FIG. 5 is another prior art apparatus. At first glance, it would appear that the apparatus would work to separate particles into two or more groups. However, upon closer inspection and modeling, the apparatus fails to separate particles into two or more groups as they are traveling through the apparatus. Particles passing through the apparatus described in will hug the surface of the wall as shown in FIG. 5 and continue down along the walls of the S-curve. The rotor (paddle wheel) in the middle of the apparatus functions to provide additional axial mixing of the air and the particles (fibers) to provide a more uniform distribution of the particles, not to separate the particles into two or more groups, especially based on inertial and/or aerodynamic characteristic differences between the particles.
As a result of the designs of the prior art apparatuses, none of them teach or function to separate the particles traveling through them into two or more groups of particles, especially where the separation is based on inertial and/or aerodynamic characteristic differences between the particles traveling through the apparatuses.
Formulators desire a high-throughput apparatus that does not utilize screens and/or sieves or have other obstructions in the main crossflow, while still being able to produce a more uniform distribution of the particles, based on size, density, aspect ratio and other properties associated with the particles.
Accordingly, there is a need for an apparatus that is capable of separating a portion of particles traveling through the apparatus from other particles traveling through the apparatus and methods for using such an apparatus.